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Hubble to Look Close for Alien Planets

Though aging, the 23-year-old Hubble Space Telescope has a new assignment in the search for planets circling other stars.

In October 2014 and February 2016, Hubble will take aim at Proxima Centauri, the nearest star to the sun.

Proxima Centauri shines brightest in this image from 1994 and the Hubble Space Telescope. Image Credit/STSI

Previous attempts to find planets around the red dwarf star, which lies 4.2 light years away, have come up empty.

With Hubble, astronomers will attempt to change that using an observing technique called “mirco lensing.”

The technique relies on a celestial alignment that places Proxima Centauri in front of another star in a way that distorts the image of the previously studied background star.

The distortions are the result of Proxima Centauri’s gravitational field warping the space around it. By comparing the distortion effects with the actual position of the background stars, astronomers can calculate the mass of Proxima Centauri. If there are planets, their gravitation fields will produce a second small distortion effect. That secondary distortion can be attributed to an object of smaller mass, or planets.

“Proxima Centauri’s trajectory offers a most interesting opportunity because of its extremely close passage to the two stars,” said Kailash Sahu, an astronomer with the Space Science Telescope Institute inBaltimore,Md. Sahu leads a team of scientists whose work on Proxima Centauri he presented Monday at the 222nd meeting of American Astronomical Society inIndianapolis.

Red dwarfs are the most common class of stars in our Milky Way galaxy. There are about 10 red dwarfs for every yellow, sun-like star.

Red dwarfs are less massive than other stars. Because lower-mass stars tend to have smaller planets, red dwarfs seem to be ideal places to go hunting for Earth-sized planets.